A brain tumor is a mass of abnormal cells that is growing in or around the brain. It develops when abnormal cells multiply for unknown reasons. Benign and malignant are terms used to describe brain tumors. Benign brain tumors are usually slow growing and have distinct borders and a normal appearance under a microscope. Malignant tumors are considered brain cancer. They tend to invade healthy areas of the brain and may grow rapidly. A benign tumor may be considered malignant if it is located in a critical area of the brain or its size is life-threatening.
Primary brain tumors start within the brain. Secondary or metastatic brain tumors come from cells which have broken away from cancers within the body and traveled to the brain. Metastatic brain tumors are always considered malignant since they evolve from cancerous cells and grow rapidly.

What Causes a Brain Tumor?

Brain tumors are usually caused by a change in genetic structure, such as mutated or missing genes. This results in abnormal cells. If abnormal cells have malignant potential, they will form a tumor when they multiply.
Changes in genetic structure may be inherited, caused by the environment, or both. Overall, a low percentage (5%) of primary brain tumors are associated with inherited genes alone. However, certain types of brain tumors, such as glioblastoma multiforme, are often associated with inherited genes.
High-dose ionizing radiation, used to treat brain tumors, may on rare occasions be associated with the production of secondary brain tumors. This most often occurs from radiation treatments that are given over time. People exposed to certain chemicals, such as petrochemicals, pesticides and formaldehyde, appear to be at higher risk of developing a malignant brain tumor than those who are not exposed. In laboratory experiments, some viruses caused brain tumors in animals. It is unknown whether viruses can cause brain tumors in humans. While the general public believes that electromagnetic fields may be connected to brain tumors, there is no research showing such a relationship.
There are many environmental and genetic factors that can cause brain tumors. However, in most cases, we just don't know what causes a brain tumor.

Tumor Grading

Tumors are graded based on their microscopic appearances. The grade indicates the level of malignancy. Tumors are graded on their mitotic index (growth rate), vascularity (blood supply), presence of a necrotic (dead cells) center, invasive potential (border distinctness) and similarity to normal cells.
Malignant tumors may contain several grades of cells. The most malignant grade of cell found determines the grade for the entire tumor, even if most of the tumor is a lower grade.
In the World Health Organization grading system, grade I tumors are the least malignant. These tumors grow slowly and microscopically appear almost normal. Surgery alone may be effective for grade I tumors. However, even a grade I tumor may be life-threatening if it is inaccessible for surgery. Grade I tumors are often associated with long-term survival.
Grade II tumors grow slightly faster than grade I tumors and have a slightly abnormal microscopic appearance. These tumors may invade surrounding normal tissue, and may recur as a grade III or higher tumor.
Grade III tumors are malignant. These tumors contain actively reproducing abnormal cells and invade surrounding normal tissue. Grade III tumors frequently recur, often as grade IV tumors.
Grade IV tumors are the most malignant and invade wide areas of surrounding normal tissue. These tumors reproduce rapidly, appear very unusual under the microscope and are necrotic in the center. Grade IV tumors cause new blood vessels to form, to help maintain their rapid growth.

Types of Treatment

Various treatments may be used to treat a benign or malignant brain tumor. The type and number of treatments given are dependent upon many factors, including the size of the tumor, location of the tumor & its growth rate and the symptoms the patient is experiencing. Patients should realize that there is more than one way to treat their tumors and should seek medical centers where many options and a continuum of treatments are available.
Open surgery or microsurgery can remove tumor partially or totally. In most of the cases there is a residual tumor. Surgical extent is limited by the structures in the vicinity f the tumor. . During open surgery it is important o spare various nerve s and exclude approach through eloquent areas. In attempt to make safe removal there is possibility to residual tumor at various locations. Some tumors can be safely excised. Important fact is that there is reduction in tumor volume and patient can get relief from pressure effects immediately after surgery.

Gamma Knife radiosurgery is a alternative to open surgery where applicable. If tumors are small benign critically located they are better treated with gamma knife as for a tumor with no massive pressure effects, opening skull and removing a part of it is not feasible. Small benign tumors like acoustic schwanomas can be primary treated with gamma knife now. Residual tumor from a large tumor surgery is also a good indication for gamma knife radiosurgery.  Deep located tumors, like chordoma, pituitary skull base meningioma can be treated with small or no morbidity, which are nearly or poorly assessable for, opens surgery.
Metastatic tumor is very good indication for gamma knife as they respond very fast and reduce in size. Gamma knife can be repeated many times for recurrent new tumors without any morbidity like dementia after while brain radiation. Primary malignant tumor may not show similar good response but can still be treated with gamma knife.

What is Gamma Knife ?
Gamma Knife treatment offers new hope for patients with brain tumors, vascular malformations and functional disorders